Conventionally, mobile terminals offer certain facilities, in particular making it possible to access services. Such facilities are, for example:
storing data of the telephone directory type, thereby facilitating access both to "basic" services and to "operator added value" services (such as, in particular, interactive services);
performing operations on "additional" services (such as, for example, call forwarding, incoming calls only, etc.); and
in mobile radio networks offering a telephony service, a service for transmitting short alphanumeric messages, together with the storing short alphanumeric messages to be transmitted or to be received by the mobile terminals.
Originally, the data relating to such facilities was stored in the mobile terminal itself. Subsequently, to obtain greater flexibility, it was proposed to store this data in the subscriber identity module.
Thus, GSM Recommendation 11.11 recommends storing the data relating to the facilities in predefined memory zones of the SIM card in the same manner as the data relating to subscriber identity is stored to ensure that the card is compatible with the various types of GSM mobile terminals suitable for receiving it.
By means of the European Telecommunications Standard (ETS), the interface between the subscriber identity module and the mobile terminal ensures that these two elements are interoperable independently of the respective manufacturers and of the operators. Thus, it is possible to take advantage of the facilities from any mobile terminal that is suitable for co-operating with such a subscriber identity module.
However, a major drawback remains. When the subscriber identity module sends a command to one or more interfaces, it does not, prior to sending the command, make sure that the type(s) of interface used can recognize the command that is sent, in particular as regards the type of graphics display. As a result, it is possible that the subscriber identity module might send commands to the terminal with which it co-operates, but that cannot be recognized by the terminal.